Data Center Frontiers website reports that the heat recycling process also positions data centres as beneficial neighbours, which could help counter growing tensions about data centres’ impact on their communities.

Denmark's unique underlying infrastructure made the project possible. In a statement, the company said, 'At all our data centres, we look to make our operations as sustainable as possible, but our ability to recycle heat from our servers is unique to our Odense data centre. This was made possible due to our close collaboration with the local district heating company Fjernvarme Fyn and its existing district heating network.'

Temperatures in most data centre hot aisles range from 27 to 46°C, still fairly low temperatures for some heat recovery strategies. Data centres can use heat pumps to boost the temperature of the waste heat, making it more valuable for use in district heating, often by transferring the heat to liquids that are easier to transport and incorporate into heating systems.

This approach requires additional ducting and pipes, but these costs can be offset by selling the heat energy to local utilities.

District heating systems like data centres because they provide steady heat 24/7.

In Denmark, Facebook is building a new heat pump facility that will capture heat from servers and prepare it for use in a local district heating system operated by utility Fjernvarme Fyn.

‘In Odense, we will direct air heated by the servers over water coils to recover the heat by raising the temperature of the water,’ Facebook says. ‘The temperature of the warm water is further raised by a heat pump facility powered from renewable energy. The hot water is then delivered to the district heating network and distributed to the local community.’

The process to deliver heat to the community starts with a wind turbine. Multiple wind turbines create and add renewable energy to the electric grid powering the facility, including servers.